Generally, a backpack design is disclosed herein. The backpack can be of any design, including single strap and double strap, and can be for any type of general or specific purpose, including but not limited to academic backpacks, business backpacks, computer or technology backpacks, audio/video equipment backpacks, luggage, travel backpacks, outdoor backpacks, hiking backpacks, survival backpacks, shooting backpacks, first-aid backpacks, medical equipment backpacks, child-care backpacks, athletic backpacks, and the like. Non-limiting examples of the athletic variety include an athletic bag, including baseball, softball, golf, lacrosse, field hockey, swimming, tennis, football, and any sport of activity having gear or equipment a user would want to carry. More specifically, a backpack design that may allow for a user to carry moderate to heavy weight over moderate distances. The term “center of gravity” (COG), as used herein refers to the center of the force of gravity through the human spine. It is to be understood that the COG may vary from individual to individual, but it is generally understood in the art that the COG of a human being in the standing position may be slightly anterior to the second sacral vertebra. This may place the COG inside the pelvis and anterior to the upper third of the sacrum in an adult. The center line of gravity may be a plumb line that is dropped from the opening of a person's ear (the COG of the skull) and travels through the COG located in the pelvis. The actual line of gravity may travel through the auricle of the ear, through the odontoid of the second cervical vertebra, the body of the seventh cervical vertebra, anterior to the thoracic spine, posterior to the third lumbar vertebra, through the COG of the entire upright human frame and down through the femoral heads. Ultimately, the line of gravity may also transect the knee and ankle joints, and may remain constant while the person is at rest and the spine is not loaded. See FIG. 1.
A person's COG may change following the placement of a typical two strap backpack, containing a moderate weight, as more weight is now present behind the line of gravity. The individual may offset this change in their COG by leaning forward slightly in an attempt to shift the weight of the pack closer to the line of gravity. In shifting the load in the backpack closer to the line of gravity, a person may now project their head forward by jutting the chin forward—the resultant posture is referred to as forward head posture (FHP). Conventional shoulder strap backpacks may promote the formation and development of FHP, and once a person develops this posture, the line of gravity may pass in front of all the anatomical structures discussed previously, thereby creating stress on those structures. The resultant posture (FHP) may be a clinical condition known to create the following: (1) compression; (2) weight bearing in the cervical and upper thoracic spine may be distributed through the bones and muscles; (3) muscle strain from the long lever fulcrum created by the FHP; and (4) damage to the spinal cord.
With respect to compression, for every inch the COG of the skull moves forward relative to the line of gravity, an additional ten pounds of compressive pressure is applied to the lower cervical intervertebral discs. Assuming the average FHP with a heavy pack is consistently about 2.5 to about 3.5 inches, the compressive forces applied to the bones and discs may be high enough to create inflammation and early onset degenerative disc disease. Compressive loads may be about 60% born by the vertebral body and disc and about 40% by the facet joints, and the magnified weight of the head created by FHP is also associated with early onset degenerative joint disease and degenerative disc disease (osteoarthritis). Muscle strain from the long lever fulcrum may cause myofascial pain. This myofascial pain may cause a wearer to increase their FHP in an attempt to relieve the discomfort. Neurologically, the development of chronic FHP has been shown to be devastating to the spinal cord, as the forward head posture and resultant loss in the normal cervical lordotic curve may be associated with neurological dysfunction and damage. Developmentally, all of the aforementioned are magnified in children and adolescents, as the developing spine is in a state of adaptation and plasticity. As such, children who spend large amounts of time in FHP, or who find themselves straining in a forward head position, may be at higher risk for the development of this posture as a permanent condition as adults. See FIG. 2.
In order to reduce the typical consequences of FHP a person may need to find ways to carry a load such that the body does not have to adopt an altered posture. This means either the load may need to be shifted or redistributed, or the line of gravity and/or the COG may need to be changed.